The GD Rom upgrade is compatible with Naomi and Naomi 2 via the option port on the top of the board. It comes with a Dimm board, very similar to the ROM board on a normal Naomi cartridge, but has RAM instead of ROMS.
RAM board Uses normal PC type DIMM's, so upgrading memory is not a problem, and relativly cheap.

The GD Rom system has a very clever way of getting around the loading delay time. When the game is initially installed, the GD ROM loads its content into the Naomi RAM. Once this is completed, the GD ROM goes into standby unless the RAM gets corupted or the game gets shut off for 72 hours or more. This does two things,

1) Eliminates loading delays completely, (after initial power up.)
2) Minimizes the on/off cycles of the GD ROM drive and greatly increasing the life of this mechanical device.

From Sega R+D - "We learned a lesson watching our coin-op competitors go through hardware hell. Many have been using off-board storage devices for years - hard drives, CD's, etc. with great success in increased content but at a tremendous cost in realiablity. These storage devices simply could not withstand the constant on/off cycling a coin-op application demands. Add to that the dirt and smoke a game has to put up with on location vs. a normal computer application and you can see how this was a problem waiting to happen"

The GD-Rom system uses an electronic "key" that plugs into the DIMM module to act as an activator, to prevent people just copying the GD-Roms, visible on the top right of the pictures. A different key is supplied with every game.

Notes : Melty Blood: Act Cadenza Ver. A is an arcade port of a PC game series and was published by Ecole Software. It removed the Story Mode visual-novel game to focus more on the fighting game engine. It completely revamped Aoko Aozaki's movelist for use as a playable character, and introduced Kouma Kishima into the series. It also introduced the Shielding mechanic (separate from EX-Shielding), as well as included various changes to the properties of characters. Storylines from Re-ACT's Arcade Mode were left intact. The logo for ver.A is notable for the Atlasia crest worn on the attire of Sion Eltnam Atlasia.

Notes : Melty Blood: Act Cadenza Ver. B is an arcade port of the PS2 game with various changes and upgrades, the most notable of which is the inclusion of 'White Len' as a playable character, with a significantly weakened moveset. It also introduced a new, fifth button to the layout that served as a contextual action depending on the situation and the direction held on the joystick when pressed, such as dodging or throwing. The logo for ver.B is notable for the silhouettes of Len and White Len.